All of Xianda_GAO_duplicate0.5321505782395719's Comments + Replies

The doomsday argument is controversial not because its conclusion is bleak but because it has some pretty hard to explain implications. Like the choice of reference class is arbitrary but affects the conclusion, it also gives some unreasonable predicting power and backward causations. Anyone trying to understand it would eventually have to reject the argument or find some way to reconcile with these implications. To me neither position are biased as long as it is sufficiently argued.

0turchin
I don't see the problems with the reference class, as I use the following conjecture: "Each reference class has its own end" and also the idea of "natural reference class" (similar to "the same computational process" in TDT): "I am randomly selected from all, who thinks about Doomsday argument". Natural reference class gives most sad predictions, as the number of people who know about DA is growing from 1983, and it implies the end soon, maybe in couple decades. Predictive power is probabilistic here and not much differ from other probabilistic prediction we could have. Backward causation is the most difficult part here, but I can't imagine now any practical example for our world. PS: I think it is clear what do I mean by "Each reference class has its own end" but some examples may be useful. For example, I have 1000 rank in all who knows DA, but 90 billions rank from all humans. In first case, DA claims that there will be around 1000 more people who know about DA, and in the second that there will be around 90 billion more humans. These claims do not contradict each other as they are probabilistic assessments with very high margin. Both predictions mean extinction in next decades or centuries. That is, changes in reference class don't change the final conclusion of DA that extinction is soon.

The post specifically explained why your properties cannot be used for predictions in the context of doomsday argument and sleeping beauty problem. I would like to know your thoughts on that.

0turchin
I can't easily find the flaw in your logic, but I don't agree with your conclusion because the randomness of my properties could be used for predictions. For example, I could predict medium human life expectancy based on (supposedly random) my age now. My age is several decades, and human life expectancy is 2 х (several decades) with 50 percent probability (and it is true). I could suggest many examples, where the randomness of my properties could be used to get predictions, even to measure the size of Earth based on my random distance from the equator. And in all cases that I could check, the DA-style logic works.

I will just post the relationship between perspective reasoning and simulation argument here.

In 2003 Nick Bostrom published his paper “Are you living in a computer simulation?”. In that paper he suggested once a civilization reaches a highly developed state it would have enough computing power to run “ancestral simulations”. Such simulations would be indistinguishable from actual reality for its occupants. Furthermore, because the potential number and levels of such simulated realities is huge, almost all observers with experiences similar to ours would b... (read more)

Yes, that's why I think to this day Elga's counter argument is still the best.

No problem, always good to have a discussion with someone serious about the subject matter.

First of all, you are right: statistic estimation and expected value in bayesian analysis are different. But that is not what I'm saying. What I'm saying is in a bayesian analysis with an uninformed prior (uniform) the case with highest probability should be the unbiased statistic estimation (it is not always so because round offs etc).

In the two urns example, I think what you meant is that using the sample of 4 balls a fair estimation would be 5 reds and 15 blues a... (read more)

Thank you for the reply. I really appreciate it since it reminds me that I have made a mistake in my argument. I didn't say SSA means reasoning as if an observer is randomly selected from all actually existent observers ( past, present and /b/future/b/).

So how do you get Beauty's prediction? If at the end of the first day you ask for a prediction on the coin, but you don't ask on the second day, then now Beauty knows that the coin flip is, as you say, yet to happen, and so she goes back to predicting 50/50. She only deviates from 50/50 when she thinks t

... (read more)
0Manfred
I always forget what the acronyms are. But the probability of H is 1/2 after learning it's Monday, any any method that says otherwise is wrong, exactly by the argument that you can flip the coin on monday right in front of SB, and if she knows it's Monday and thinks it's not a 50/50 flip, her probability assignment is bad.

Ok, I should have use my words more carefully. We meant the same thing. When I say beauty think the 8 rooms are unbiased sample I meant what I listed as C: It is an unbiased for the other 80 rooms. So yes to what you said, sorry for the confusion. it is obvious because it is a simple random sample chosen from the 80 rooms. So that part there is no disagreement. The disagreement between the two is about whether or not the 9 rooms are an unbiased sample. Beauty as a thirder should not think it is unbiased but bases her estimation on it anyway to answer the q... (read more)

Very clear argument and many good points. Appreciate the effort.

Regarding your position on thirders vs halfers, I think it is a completely reasonable position and I agree with the analysis about when halfers are correct and when thirders are correct. However to me it seems to treat Sleeping Beauty more as a decision making problem rather than a probability problem. Maybe one's credence without relating consequences is not defined. However that seems counter intuitive to me. Naturally one should have a belief about the situation and her decisions should dep... (read more)

0simon
Thanks for the kind words. However, I don't agree. The additional 8 rooms is an unbiased sample of the remaining 80 rooms for beauty. The additional 8 rooms is only an unbiased sample of the full set of 81 rooms for beauty if the first room is also an unbiased sample (but I would not consider it a sample but part of the prior). Actually I found a better argument against your original anti-thirder argument, regardless of where the prior/posterior line is drawn: Imagine that the selector happened to encounter a red room first, before checking out the other 8 rooms. At this point in time, the selector's state of knowledge about the rooms, regardless of what you consider prior and what posterior, is in the same position as beauty's after she wakes up. (from the thirder perspective, which I generally agree with in this case). Then they both sample 8 more rooms. The selector considers this an unbiased sample of the remaining 80 rooms. After both have taken this additional sample of 8, they again agree. Since they still agree, beauty must also consider the 8 rooms to be an unbiased sample of the remaining 80 rooms. Beauty's reasoning and the selector's are the same regarding the additional 8 rooms, and Beauty has no more "supernatural predicting power" than the selector. About only thirding getting the attention: my apologies for contributing to this asymetry. For me, the issue is, I found the perspectivism posts at least initially hard to understand, and since subjectively I feel I already know the correct way to handle this sort of problem, that reduces my motivation to persevere and figure out what you are saying. I'll try to get around to carefully reading them and providing some response eventually (no time right now).

Yes, I have given a long run frequency argument for halving in part I. Sadly that part have not gotten any attention. My entire argument is about the importance of perspective disagreement in SBP. This counter argument is actually the less important part.

OK, I misunderstood. I interpreted the coin is biased 1/3 to 2/3 but we don't know which side it favours. If we start from uniform (1/2 to H and 1/2 to T), then the maximum likelihood is Tails.

Unless I misunderstood again, you mean there is a coin we want to guess its natural chance (forgive me if I'm misusing terms here). We do know its chance is bounded between 1/3 and 2/3. In this case yes, the statistical estimate is 0 while the maximum likelihood is 1/3. However it is obviously due to the use of a informed prior (that we know it is between 1/3 and 2... (read more)

0cousin_it
Interesting. I guess the right question is, if you insist on a frequentist argument, how simple can you make it? Like I said, I don't expect things like unbiased estimates to behave intuitively. Can you make the argument about long run frequencies only? That would go a long way in convincing me that you found a genuine contradiction.

Maximum likelihood is indeed 0 or Tails, assuming we start from a uniform prior. 1/3 is the expected value. Ask yourself this, after seeing a tail what should you guess for the next toss result to have maximum likelihood of being correct?

If halfers reasoning applies to both Bayesian and Frequentist while SIA is only good in Bayesian isn't it quite alarming to say the least?

0cousin_it
The 0 isn't a prediction of the next coin toss, it's an unbiased estimate of the coin parameter which is guaranteed to lie between 1/3 and 2/3. That's the problem! Depending on the randomness in the sample, an unbiased estimate of unknown parameter X could be smaller or larger than literally all possible values of X. Since in the post you use unbiased estimates and expect them to behave reasonably, I thought this example would be relevant. Hopefully that makes it clearer why Bayesians wouldn't agree that frequentism+halfism is coherent. They think frequentism is incoherent enough on its own :-)

Nothing shameful on that. Similar arguments, which Jacob Ross categorized as "hypothetical priors" by adding another waking in case of H, have not been a main focus of discussion in literatures for the recent years. I would imagine most people haven't read that.

In fact you should take it as a compliment. Some academic who probably spent a lot of time on it came up the same argument as you did.

Appreciate the effort. Especially about the calculation part. I am no expert on coding. But from my limited knowledge on python the calculation looks correct to me. I want to point out for the direct calculation formulation like this+choose+3)++((81-r)+choose+6)),+r%3D3+to+75)+%2F+(sum+(+((r)+choose+3)++((81-r)+choose+6)),+r%3D3+to+75)) gives the same answer. I would say it reflect SIA reasoning more and resemble your code better as well. Basically it shows under SIA beauty should treat her own room the same way as the other 8 rooms.

The part explaining th... (read more)

0cousin_it
Mathematically, maximum likelihood and unbiased estimates are well defined, but Bayesians don't expect them to always agree with intuition. For example, imagine you have a coin whose parameter is known to be between 1/3 and 2/3. After seeing one tails, an unbiased estimate of the coin's parameter is 0 (lower than all possible parameter values) and the maximum likelihood estimate is 1/3 (jumping to extremes after seeing a tiny bit of information). Bayesian expected values don't have such problems. You can stop kicking the sand castle of frequentism+SIA, it never had strong defenders anyway. Bayes+SIA is the strong inconvenient position you should engage with.

For the priors,. I would consider Beauty's expectations from the problem definition before she takes a look at anything to be a prior, i.e. she expects 81 times higher probability of R=81 than R=1 right from the start.

In the original sleeping beauty problem, what is the prior for H according to a thirder? It must be 1/2. In fact saying she expects 2 times higher probability of T than H right from the start means she should conclude P(H)=1/3 before going to sleep on Sunday. That is used as a counter argument by halfers. Thirders are arguing after waking ... (read more)

0simon
Well argued, you've convinced me that most people would probably define what's prior and what's posterior the way you say. Nonetheless, I don't agree that what's prior and what's posterior should be defined the way you say. I see this sort of info as better thought of as a prior (precisely because waking up shouldn't be thought of as new info) [edit: clarification below]. I don't regard the mere fact that the brain instantiating the mind having this info is physically continuous with an earlier-in-time brain instantiating a mind with different info as sufficient to not make it better thought of as a prior. Some clarification on my actual beliefs here: I'm not a conventional thirder believing in the conventional SIA. I prefer, let's call it, "instrumental epistemic rationality". I weight observers, not necessarily equally, but according to how much I care about the accuracy of the relevant beliefs of that potential observer. If I care equally about the beliefs of the different potential observers, then this reduces to SIA. But there are many circumstances where one would not care equally, e.g. one is in a simulation and another is not, or one is a Boltzmann brain and another is not. Now, I generally think that thirdism is correct, because I think that, given the problem definition, for most purposes it's more reasonable to value the correctness of the observers equally in a sleeping beauty type problem. E.g. if Omega is going to bet with each observer, and beauty's future self collects the sum of the earnings of both observers in the case there are two of them, then 1/3 is correct. But if e.g. the first instance of the two observer case is valued at zero, or if for some bizarre reason you care equally about the average of the correctness of the observers in each universe regardless of differences in numbers, then 1/2 is correct. Now, I'll deal with your last paragraph from my perspective, The first room isn't a sample, it's guaranteed red. If you do regard it as a

This argument is the same as Cian Dorr's version with a weaker amnesia drug. In that experiment a weaker amnesia drug is used on beauty if Heads which only delays the recollection of memory for a few minutes, just like in your case the memory is delayed until the message is checked.

This argument was published in 2002. It is available before majority of the literature on the topic is published. Suffice to say it is not convincing to halfers. Even supporter like Terry Horgan admit the argument is suggestive and could run a serious risk of slippery slope.

0cousin_it
Thank you for the reference! Indeed it's very similar, the only difference is that my version relies on the beauty's precommitment instead of the experimenter, but that probably doesn't matter. Shame on me for not reading enough.

In both boy or girl puzzle and Monty hall problem the main point is "how" the new information is obtained. Is the mathematician randomly picking a child and mentioning its gender, or is he purposely checking for a boy among his children. Does the host know what's behind the door and always reveal a goat, or does he simple randomly opens a door and it turns out to be a goat. Or in statistic terms: how is the sample drawn. Once that is clear bayesian and statistics gives the same result. Of course if one start from a wrong assumption about the samp... (read more)

0cousin_it
If by "estimate" you mean "highest credence", the short answer is that Bayesians usually don't use such tools (maximum likelihood, unbiased estimates, etc.) They use plain old expected values instead. After waking up in a red room and then opening 2 red and 6 blue rooms, a Bayesian thirder will believe the expected value of R to be 321/11, which is a bit over 29. I calculated it directly and then checked with a numerical simulation. It's easy to explain why the expected value isn't 27 (proportional to the fraction of red in the sample). Consider the case where all 9 rooms seen are red. Should a Bayesian then believe that the expected value of R is 81? No way! That would imply believing R=81 with probability 100%, because any nonzero credence for R<81 would lead to lower expected value. That's way overconfident after seeing only 9 rooms, so the right expected value must be lower. You can try calculating it, it's a nice exercise.

Both claims are very bold, both unsubstantiated.

First of all, SIA in bayesian is up to debate. That's the whole point of halfer/thirder disagreement. A "consistent" reasoning is not necessarily correct. Halfers are also consistent.

Second of all, the statistics involved is as basic as it gets. You are saying with a simple random sample of 9 rooms with 3 reds, it is wrong to estimate the population have 30% reds. Yet no argument is given.

Also please take no offence, but I am not going to continue this discussion we are having. All I have been doing is explaining the same points again and again. While the replies I got are short and effortless. I feel this is no longer productive.

0cousin_it
My replies to you are short, but they weren't simple to write. Each of them took at least 30 minutes of work, condensing the issues in the most clear way. Apologies if that didn't come across. Maybe a longer explanation would help? Here goes: In the latest reply I tried to hint that many people use "simple statistics" in a way that disagrees with Bayes, and usually they turn out to be wrong in the end. One example is the boy or girl puzzle, which Eliezer mentioned here. Monty Hall variations are another well known example, they lead to many plausible-sounding frequentist intuitions, which are wrong while Bayes is reliably right. After you've faced enough such puzzles, you learn how to respond. Someone tells me, hey, look at this frequentist argument, it gives a weird result! And I reply, sorry, but if you can't capture the weirdness in a Bayesian way, then no sale. If your ad hoc tools are correct, they should translate to the Bayes language easily. If translating is harder than you thought, you should get worried, not confident. To put it another way, you've been talking about supernatural predictive power. But if it looks supernatural only to non-Bayesians, while Bayesians see nothing wrong, it must be very supernatural indeed! The best way to make sure it's not an illusion is to try explaining the supernaturalness to a Bayesian. That's what I've been asking you to do.

Ok, let's slow down. First of all there are two type of analysis going on. One is bayesian analysis which you are focusing on. The other is simple statistics, which I am saying thirders and SIA are having troubles with.

If there are 100 rooms either red or blue. You randomly open 10 of them and saw 8 red and 2 blue. Here you can start a bayesian analysis (with an uniform prior obviously) and construct the pdf. I'm going to skip the calculation and just want to point out R=80 would have the highest probability. Now instead of going the bayesian way you can a... (read more)

0cousin_it
If Bayes + SIA gives a consistent answer, while "simple statistics" + SIA gives a contradiction, it looks like "simple statistics" is at fault, not SIA.

Thirder and the selector have the exact same prior and posteriors. Their bayesian analysis are exactly the same.

Think from the selector's perspective. He randomly opens 9 out of the 81 rooms and found 3 red. Say he decided to perform a bayesian analysis. As stated in the question he starts from an uniform prior and updates it with the 9 rooms as new information. I will skip the calculation but in the end he concluded R=27 has the highest probability. Now think from the thirder's perspective. As SIA states she is treating her own room as randomly selected ... (read more)

1simon
We may just be arguing over definintions. For the priors,. I would consider Beauty's expectations from the problem definition before she takes a look at anything to be a prior, i.e. she expects 81 times higher probability of R=81 than R=1 right from the start. SIA states that you should expect to be randomly selected from the set of possible observers. That doesn't imply that you are in a postion randomly selected from some other set. (only if observers are randomly selected from that set). Here, observers start in red rooms only, so clearly, you can't expect your room to be randomly selected colour if you believe in SIA.

Maybe it is my English. In this case, you wake up in a red room, and open another room and found it to be blue. As SIA states, you should treat both rooms as they are randomly selected from all rooms. So in the 2 randomly selected rooms 1 is red and 1 is blue. Hence 50%.

0cousin_it
It seems like you're changing the definition of "fraction in the hand" to also include the room you woke up in, but keep the definition of "fraction in the bag" without that room. So now the "hand" contains a bean that didn't come from the "bag". That ain't gonna work. Maybe let's stick to your old definitions: You said there was a difference between "fraction in the hand" and "fraction in the bag", which was predictable before you grab. But to a thirder, before you grab, the expected values of both fractions are 2/3. Can you explain what difference you saw?
0[anonymous]
Lets say you wake up in room 1 which is red, then open room 2 which is blue, and room 3 stays unopened. Are you using {1,2} as a random sample that predicts the frequency of red in {2,3}? How on Earth is that reasonable?

Sure. Although I want to point out the estimation would be very rough. That is just the nature of statistics with very small sample size.

The "beans in the hand" would be the random other room you open. The "beans in the bag" would be the two other rooms.

Let's say you open another room and found it red. If I'm correct as a thirder you would give R=3 a probability of 3/4, R=2 a probability of 1/4. This can be explained by SIA: this is randomly selecting 2 rooms out of the 3 and they are both red. 3 ways for it to happen if R=3 and 1 way... (read more)

0cousin_it
That seems to be our main disagreement. By my calculation, upon waking up, a thirder believes that number to be 66.6%. I'm not sure how you get 50% from SIA.

Very clear argument, thank you for the reply.

The question is if we do not use bayesian reasoning, just use statistics analysis can we still get an unbiased estimation? The answer is of course yes. Using fair sample to estimate population is as standard as it gets. The main argument is of course what is the fair sample. Depending on the answer we get estimation of r=21 or 27 respectively.

SIA states we should treat beauty's own room as a randomly selected from all rooms. By applying this idea in bayesian analysis is how we get thirdism. To oversimplify it:... (read more)

0Manfred
Sorry for the slow reply. The 8 rooms are definitely the unbiased sample (of your rooms with one red room subtracted). I think you are making two mistakes: First, I think you're too focused on the nice properties of an unbiased sample. You can take an unbiased sample all you want, but if we know information in addition to the sample, our best estimate might not be the average of the sample! Suppose we have two urns, urn A has 10 red balls and 10 blue balls, while urn B has 5 red balls and 15 blue balls. We choose an urn by rolling a die, such that we have a 5/6 chance of choosing urn A and a 1/6 chance of choosing urn B. Then we take a fair, unbiased sample of 4 balls from whatever urn we chose. Suppose we draw out 1 red ball and 3 blue balls. Since this is an unbiased sample, does the process that you are calling "statistical analysis" have to estimate that we were drawing from urn B? Second, you are trying too hard to make everything about the rooms. It's like someone was doing the problem with two urns from the previous paragraph, but tried to mathematically arrive at the answer only as a function of the number of red balls drawn, without making any reference to the process that causes them to draw from urn A vs. urn B. And they come up with several different ideas about what the function could be, and they call those functions "the Two-Thirds-B-er method" and "the Four-Tenths-B-er method." When really, both methods are incomplete because they fail to take into account what we know about how we picked the urn to draw from. Think of it like this: if Beauty opens 8 doors and they're all red, and then she goes to open a ninth door, how likely should she think it is to be red? 100%, or something smaller than 100%? For predictions, we use the average of a probability distribution, not just its highest point.

Imagine a bag of red and blue beans. You are about to take a random sample by blindly take a handful out of the bag. All else equal, one should expect the fraction of red beans in your hand is going to be the same as its fraction in the bag. Now someone comes along and says based on his calculation you are most likely to have a lower faction of red beans in your hand than in the bag. He is telling you this even before you deciding where in the bag you are going to grab. He is either (a) having supernatural predicting power or (b) wrong in his reasoning.

I think it is safe to say he is wrong in his reasoning.

0cousin_it
In the example I outlined with three rooms, can you give numerical values for "the fraction in the hand" and "the fraction in the bag"?

What you said is correct. I'm arguing because the 8 rooms is obviously an unbiased sample, the 9 rooms cannot be. Which means beauty cannot treat her own room as a randomly selected room from all rooms as SIA suggests. The entire thought experiment is a reductio against thirders in the sleeping beauty problem. It also argues that beauty and the selector, even free to communicate and having identical information, would still disagree on the estimation of R.

0cousin_it
Can you explain exactly what the supernatural powers are? For simplicity let's assume three rooms, with the number of red rooms uniformly distributed between 1 and 3. After waking up in a red room, and just before opening a random other room, a thirder expects it to be red with probability 2/3. You seem to say that it can't be right, but I can't tell if you consider it too low or too high, and why?

First thing I want to say is that I do not have a mathematics or philosophy degree. I come from an engineering background. I consider myself as a hobbyist rationalist. English is not my first language, so pease forgive me when I make grammar mistakes.

The reason I've come to LW is because I believe I have something of value to contribute to the discussion of the Sleeping Beauty Problem. I tried to get some feedback by posting on reddit, however maybe due to the length of it I get few responses. I find LW through google and the discussion here is much more ... (read more)

0Elo
You should have karma to post now.